Cracks in the Blacktop

There are several cracks on roads, parking lots, and on the playground blacktop. Weathering happens in rocks when water seeps into cracks and freezes. Students will be discovering why and how this happens.

Driving Question

• What causes cracks in concrete or on blacktop?

Probing Questions

• What do you notice about the blacktop?
• What might cause rocks to crack or break?
• How could weather affect the blacktop?

Classroom Suggestions

Students could:

• Take a walk outside on the playground and take notes on what they notice while looking at the concrete or blacktop. Students can also note other things that have weathered as they observe.
• Freeze water bottles and take measurements before the water bottle is frozen, while the water bottle is frozen, and after the water bottle thaws. One water bottle should be filled all the way to the rim so that it explodes, showing that water expands when it freezes and drawing a parallel to what could happen to a rock.

Relevant Related Resources

Weathering and Erosion | Generation Genius: Video and lesson materials for kids on weathering and erosion. 
Will a Mountain Last Forever? | Mystery Science: A lesson on weathering and erosion. 
Physical Weathering at Work | ReadWorks: An article for kids on weathering and erosion.